Apparatus for applying plasticizer to filter tow



J. F. CAINES 3,157,536

APPARATUS FOR APPLYING PLASTICIZER T0 FILTER TOW Nov. 17, 1964 Filed July 20, 1962 v [NV EV TOR. fljiw/ JamesECaines Amms United States Patent Ofifice 3,l?,53 Patented Nov. 1'7, 1954 3,157,536 APPARATUS FGR APPLYING PLASTTCEZER T0 FILTER TGW James F. Caines, Kingsport, Tenn, assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Fiied July 20, 1962, Ser. No. 211,326 4 Claims. (Cl. 118-225) This invention relates to applying plasticizer to continuous multifilament tow and more particularly to apparatus for applying plasticizer to cellulose ester tow from which tobacco smoke filters suitable for use with cigarettes, pipes and cigar holders can be made.

This invention is especially concerned with a simplified apparatus for applying plasticizer to cellulose acetate continuous multifilament tow before the blooming of the tow which blooming is accomplished by the cylindrical venturi jet method described in Caines et al. US. patent application Serial No. 27,091, filed May 5, 1960, now US. Patent 3,099,594 of July 30, 1963, and entitled Method and Apparatus for Blooming Filter Tow.

Prior to the present invention, a complex array of rolls, heaters, banding jets, blooming jets, spray guns, plasticizer booths and exhaust systems had to be employed to process such multifilament cellulose acetate tow into filter plugs. Such process and apparatus are shown for example in Crawford Patent 2,900,988 of August 25, 1959, and Jackson 2,828,752 of April 4, 1958. In Dyer and Gallagher application Serial No. 736,900, filed May 21, 1958, now US. Patent 3,079,663 of March 5, 1963, apparatus means is described for improving the processing of low denier per filament cellulose acetate tows. The apparatus there employed was not materially simplified over the earlier disclosures referred to above and a more simple apparatus was desired in cigarette filter plug manufacture.

One disadvantage of the prior art apparatus and process was the need to spread out the tow into a flat band in order that the plasticizer could be uniformly applied to the filaments comprising the band. This leads to another disadvantage where false or very slight real twist occurred in the tow. When such twist was not removed from the tow, after it was withdrawn from the bale and before it reached the withdrawal rolls, the twist continued through the apparatus in the form of a cross-over which might be visualized as a ribbon twisted 180 C. These cross-over filaments consequently did not bloom to the same degree as the untwisted substantially parallel filaments and therefore received an uneven application of plasticizer. Filter plugs made from this twisted portion of the tow were usually not up to standard quality.

The Caines et a1. invention described in said Serial No. 27,091 thus represented a considerable advance in the art in that the tow was to be opened and bloomed in a round form. Thus, the effect of any slight twist in a tow was eliminated. Since the tow was always in the same round form that it appears in the filter plugs, the apparatus would thus be simplified. However, the difiiculties of processing tow in round form have been the lack of suitable equipment adequate to bloom the tow and to apply'plasticizer uniformly to the round tow. These difficulties have been overcome by the present invention.

An object of the present invention, therefore, is to provide a simplified apparatus for distributing plasticizer on continuous multifilament tow. Another object is to provide apparatus for, applying plasticizer to the tow just before the entrance of the tow into the cylindrical venturi blooming jet wherein the plasticizer is further distributed over the filaments of the tow. Other objects will appear hereinafter.

The present invention is described in more detail in the following paragraphs which include reference to the related drawings in which:

FIGURE 1 is a view of the novel apparatus for applying plasticizer to the tow associated with the cylindrical venturi blooming jet;

FIGURE 2 is a view, partly in section, of one form of the plasticizer applicator;

FIGURE 3 is a cross-section view of the plasticizer applicator taken on lines 33 of FIGURE 2;

FIGURE 4 is a view, partly in section, of another form of the plasticizer applicator;

FIGURE 5 is a cross-section view of the plasticizer applicator taken on the lines 55 of FIGURE 4;

Referring to FIGURE 1, the apparatus there shown comprises a plasticizer supply tank 10 in fluid communication through conduit 11 with a pair of metering gear pumps 12. The output of the two metering gear pumps 12 flows through the pair of flexible hoses 13 to a pair of plasticizer applicators 14. The plasticizer applicators are respectively rigidly fastened to an arm 15 pivotally about an axle 16. As shown in FIGURE 1, the two applicators respectively apply the plasticizer to the opposite sides of the tow 19. At one end of the arm 15, the piston rod of an air cylinder 17 is connected through a hinge pin, not shown. The air cylinder 17 is attached to the machine frame, not shown, by a hinge pin 18. The air cylinder 17 when actuated to thrust the piston rod downwardly moves the pair of plasticizer applicators 14 around the axis 16 so that they assume the position shown in the dotted lines as represented by 14a, and the connecting arm is shown at 15a. The air cylinder 17 can be actuated by means, not shown, independently of the operation of the remainder of the apparatus, or may be coordinated with a start-stop means of the tow blooming jet 22 so as to rotate automatically the pair of plasticizer applicators 14 out of contact with the tow 19 when the device is stopped and into contact with the tow 19 as the blooming jet 22 is started. Instead of an air operated piston, one may employ a solenoid operated piston. Rotating the plasticizer applicators 14 out of contact with the tow 19 prevents wicking of too much plasticizer onto spots on the tow 19 when the tow is not moving past the applicators.

The tow 19 is drawn from a bale, not shown, by means of coacting rolis 21 which preferably are arranged to turn by means, not shown, when the blooming jet 22 is in operation and passes under the first plasticizer applicator and over the second plasticizer applicator. In this way, plasticizer is spread on each side of the multifilament tow. One or both of metal rolls 21 may be rubber covered. The tow having plasticizer thereon is then passed into cylindrical venturi blooming jet 22. The plasticized and bloomed tow exits from blooming jet 22 where the fingers 56 retain it to a desired shape.

The details of the two types of plasticizer applicators 14 are shown in more detail in FIGURES 2 and 3 and in FIGURES 4 and 5. As shown in FIGURE 2, the plasticizer applicator 14 comprises a stainless steel tube 30 having a narrow 0.01 inch to 0.06 inch slit 31 cut longitudinally along one side. Gne end of the tube 30 is closed at 32 and the other end while also closed is provided with a connection for the flexible tube 13 through which plasticizer is forced under pressure into the applicator. A stainless steel wire mesh 33 is positioned over the slot 31 and is held in position by clamps 35. The stainless steel mesh prevents wear and minimizes tension. The structure of the plasticizer applicator is further shown in FIGURE 3 which is a section taken on lines 33.

Referring to FIGURE 4, the plasticizer applicator 40 is similar to that of FIGURE 2 except that a felt layer is positioned beneath the screen and over the exit slit.

As shown in FIGURE 2, the applicator comprises the stainless steel tube 46 with the narrow slit 41 along one' side. One side of tube 4%) is closed at 42 and the other end while closed is provided with a connection for the fiexible tube 13 through which plasticizer is forced under pressure into the applicatortube. A porous felt layer 43 is positioned over slit 41 and a wire screen 44 is posi- The jet serves three purposes.- It blooms the tow by rearranging the individual filaments. It evenly redistributes the plasticizer which has already been applied to the tow. It forces the tow into the bustle forming it tioned over the felt 43; These are held in position by clamps 45 This modificatio'n of the plasticizer applicator is further illustrated in FIGURE 5 which is a secsure is applied to the jet which causes the tow tobe come taut in the space between the nip of rolls 21 and the jet 22. At this point, piston 17 is actuated to position the plasticizer applicators 14 into contact with the moving tow and gear pumps 12 are actuated to draw plasticizer from supply it and force it through flexible hoses 13 to'the respective plasticizer applicators 14. The

moving tow therefore will be coated on both sides with a coating of plasticizer. The tow passes over the plasticizer applicators as a flat ribbon about /2 inchwide, but as it enters the jet 22, it is folded into a cylindrical form. Thus, although every filament may not receive an application of plasticizer from the two applicators, any local point in the cross section of the tow now in the jet 2 has filaments that have received plasticizer.

The amount of plasticizer on these filaments at such places is in general in excess of that required to bond the filaments together adequately. The tow enters the jet at the nozzle inlet and the air and tow come together i at the orifice. Here the individual filaments are violently rearranged and also in the tapereddischarge section of V the jet body. The tow accumulates in the bustle of the jet between the bustle fingers 56. By holding the tow in the bustle for a short period of time allows the maxi-.

mum exposure of the tow to the compressed air. Now, as "the tow is subjected to this high velocity explosive blast of air in the bustle the excess plasticizer on these filaments is blown off and impinges on filaments that have not picked up plasticizer when passing in contact with the plasticizer applicators 14. Thus, an aerosol of plasticizer is generated within the jet 22 and an essentially completely uniform plasticizer distribution is achieved on ail filaments in the tow by the time it emerges from thejet.

The large mass of bloomed filaments retarded by the bustle fingers 56 and the exit of the venturi tube assures that only an insignificantamount of most plasticizers will escape to. the atmosphere. This is a result of'the fact that while the mass of emergingfilaments not only acts as a highly-efiicient filter medium for the plasticizer, the

exhaust air from the jet is so retarded and slowed down as it emerges from the mass of bloomed filaments that it no longer has sufficient velocity emerging to'blow oft and remove plasticizer from the surface of the bloomed fila- BEGINS; Without the presence of the'retarded bustle fin- .gers 56, the filter mass would not be formed at the exit of the jet and poorer distribution of the plasticizer would ensue as well as losses of plasticizer to the atmosphere.

The plasticized tow may now be ,conducted to withdrawing rolls and into a condensing tru'mpet which forms theptow into a cylindrical rod which then'isintroduced 'into'a conventional cigarette plug making machine. "The apparatus described in this paragraph not being 'a part 7 of the present invention is not shownin the accompanying drawings. s 7

into a tangled mass ofgfilaments. Much of the original crimp in the tow is restored to the tow as it passes through i the hustle and accounts for the, increased hardness of the rods produced by this apparatus.

Suitable plasticizers such as methyl phthalyl ethyl glycolate (carbethoxymethyl methyl phthalate) dibutyl phthalate, tripropionin, triacetin and acetyl triethyl citrate may be employed. Theplasticizer is applied until the' tow contains 4 to 3Q%, preferably 6-15 by weight of plasticizer.

The invention has been described in detail with par- 7 ticular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in'the appended claims. r

' I'claim: a V

1. Apparatus for applying plasticizer to a band of multifilament tow comprising a tube with closed ends having a slot orifice extending along a substantial portion of the length thereof, a conduit entering one end of said tube for conducting plasticizer therein, and a wire mesh positioned over said slot to'support the .tow out p of contact with said slot orifice.

2. Apparatus for applying plasticizer to bandof multifilament tow comprising a pair of applicators rerespectively positioned 'on tthe opposite sides of the tow and respectively mounted at'the ends of a rotatable arm, means for continuously moving the tow past the applicators, means for rotating; the applicators into and out of contact with the moving tow, each applicator comprising a tube with closed ends having a slot orifice extending along a substantial portion of the length thereof, a

conduit entering one end of said tube, a wire mesh posi tioned over said slot to support the tow out of contact with said slot orifice and means for forcing plasticizer into the conduit and. tube and through the slot orifices" and meshes to apply plasticizer tosaiid moving tow."

3. Apparatus for applying plasticizer to a band of multifilament tow comprising a tube with closed ends having a slot orifice extending along a substantial portion of the length thereof, a conduit entering one end of said tube for conducting plasticizer therein, a porous felt layer over said slot orifice and a wire mesh posi tioned over said felt layer to support the towlwhen the plasticizeriis applied to said tow.

4. Apparatus for applying plasticizerv to a band of.

multifilament tow comprising a'plasticizer supply tank containing plasticizer, a pair of applicatorsrespective'ly positioned on the opposite sides of the tow and respectively mounted at the ends of a rotatable arm, means for continuously moving the tow. past the applicators,

means for rotating the applicators'into and out of contact with'the moving tow, each applicator comprising a tubewith closed ends having a slot'orifice extending along a substantial portion of the length. thereof, .a v flexible conduit entering one end of said tube and con nected to the plasticizer supplytank, a wire mesh positioned over said slot to support the tow out of contact 'with said'slot orifice andrneans for forcing plasticizer? into the conduits and applicators and through the ,slot' orifices and meshes to contact said moving tow.

References Cited in the file of this patent UNITED STATES, PATENTS 7 366,857 7 McGraw July 19, 188 668,956 Enyeart rebozaiao 1,454,363 a Winchenba'ught t al. May 8, 1923 Beardsell et a1. Jan. 1,1957. 

1. APPARATUS FOR APPLYING PLASTICIZER TO A BAND OF MULTIFILAMENT TOW COMPRISING A TUBE WITH CLOSED ENDS HAVING A SLOT ORIFICE EXTENDING ALONG A SUBSTANTIAL PORTION OF THE LENGTH THEREOF, A CONDUTI ENTERING ONE END OF SAID TUBE FOR CONDUCTING PLASTICIZER THEREIN, AND A WIRE MESH POSITIONED OVER SAID SLOT TO SUPPORT THE TOW OUT OF CONTACT WITH SAID SLOT ORIFICE. 